Pick Confirm at Parcel/Box level

One of my client has made a change request on a customized development.

The actual customization contains the following steps:
1. after pick release of a sales order, the delivery details are sent to third party system (Logistics mgt)
2. The latter sends back a file specifying the proposed allocations for the move order lines and the box/es necessary.

Hence we did the allocation, create LPN, pick confirm and ship confirm... it works well.

The new Request is to pick confirm at Box level which is different with what we did before ( at move order line).

API used: inv_pick_wave_pick_confirm_pub.pick_confirm

I would like to request your help for this point as actually i can't find an API which will split my move order lines. As I should be able to allocate a box and pick that box even if my shipped quantity has not been completed yet!

Possible scenario:
The allocation and pick confirm can correspond to a partial quantity of a delivery line.
For instance:
- Initial delivery line quantity: 100
- This delivery line will be picked by 2 boxes (60 + 40)
- The first box is confirmed: Qty: 60
- The move order line is partially allocated, the delivery line is split, and the first allocation is transacted as pick-confirmed
- The second delivery line must remained assigned to the delivery, and at status "Released to Warehouse"
- The second box is then pick-confirmed, qty: 40: this qty is allocated and pick-confirmed.